Ignition distributor with contact breaker assembly mounting plate

ABSTRACT

An ignition distributor for an internal combustion engine spark ignition system includes a hollow casing having journalled for rotation therein a cam shaft having a cam portion. Secured within the casing is a contact breaker assembly mounting plate, the mounting plate being spaced from the level of the cam portion of the cam shaft. Mounted on the mounting plate is a spacer member, and secured to the mounting plate by way of the spacer member is a contact breaker assembly. The dimensions of the spacer assembly are such that a cam follower of the contact breaker assembly is aligned with, and engageable with the cam portion of the cam shaft.

United States Patent Rees Mar. 5, 1974 [54] IGNITION DISTRIBUTOR WITII CONTACT R23,749 12/1953 Brunk 200/31 DP BREAKER M Y MOUNTING PLATE 3,091,672 5/1963 Longenecker 200/31 DP UX 2,730,583 1 1956 Brunk 200 31 DP [75] Inventor: Alfred Rees, Birmingham, England [73] Assignee: Joseph Lucas (Electrical) Limited, Examinepdames Scott Bi i h E l d Attorney, Agent, or Firml-Iolman & Stern [22] Filed. Jan. 15, 1973 ABSTRACT [21} Appl' 323382 An ignition distributor for an internal combustion en- 1 gine spark ignition system includes a hollow casing [30] Foreign Application Priority Data having joumalled for rotation therein a cam shaft hav- Jan. 15, 1972 Great Britain, 2011/72 ing a cam p Secured Within the easing is a contact breaker assembly mounting plate, the mount- 52 us. Cl 200/19 R, 200/30 A, 200/31 DP s Plate being spaced from the level of the cam p 51 Int. Cl. H01h 19/62 of the em shaft Mounted on the mounting Plate 5 Field f Search. 200/19 19 A, 30 A 0 A A is a spacer member, and secured to the mounting plate 200 31 DP by way of the spacer member is a contact breakerassembly. The dimensions of thespacer assembly are 5 R f e Cited such that a cam follower of the contact breaker as- UNITED STATES PATENTS sembly is aligned with, and engageable with the cam portion of the cam shaft. 3,688,392 9/1972 Cooksey 200/l9 R X 2,896,035 2 Claims, 5 Drawing Figures 7/1959 Harrington et al 200/30 AA PATENTEUMAR 51974 3795.778

sum a nr- 2 IGNITION DISTRIBUTOR WITH CONTACT BREAKER ASSEMBLY MOUNTING PLATE This invention relates to ignition distributors for internal combustion engine spark ignition systems.

There are two common types of ignition distributor, one where the contact breaker assembly of the distributor is mounted for angular movement around the axis of the distributor cam shaft and a secondtype where the contact breaker assembly is fixed relative to the casing of the distributor. A problem exists in standardization of the distributor components and it is an object of the present invention to minimise this problem.

An ignition distributor according to the invention includes a hollow casing, a shaft mounted for rotation in the casing and having a cam portion, a contact breaker assembly mounting plate secured within the casing and spaced from the level of the cam portion of the shaft, a contact breaker assembly, and a spacer member secured to the mounting plate and supporting the contact breaker assembly, the dimensions of the spacer being such that a cam follower of the contact breaker assem bly is engageable with the cam portion of said shaft.

Desirably the mounting plate is arranged to be capable of rotatably supporting a timing plate carrying a contact breaker assembly.

One example of the invention is illustrated in the accompanying drawings wherein:

FIG. 1 is a plan view partly in section of an ignition distributor with the top cover and the cam shaft thereof removed,

FIG. 2 is a sectional view on the line A-A in FIG.

FIG. 3 is a plan view of an alternative form of the spacer shown in FIG. 1 and 2,

FIG. 4 is a side view of the spacer shown in FIG. 3,

and,

FIG. 5 is a sectional view on the line 5-5 in FIG. 3.

Referring to the drawings, the ignition distributor which is for use in the spark ignition system of an internal combustion engine includes ahollow metal casing having journalled for rotation therein an axially extending cam shaft 11. Rigidly secured to the casing 11 and extending transversely relative to the axis of the casing is an annular mounting plate 12. The wall of the central aperture 13 of the mounting plate 12 is extended to define an upwardly directed cylindrical spigot 14 the purpose of which will be described later. Thecam shaft 11 extends through the spigot 14 and has a cam portion 11a spaced above the level of the plate 12. The portion 11a of the shaft 11 is the portion which operates the contact breaker assembly 15 of the distributor a cam follower 16 of the assembly 15 engaging the surface of the portion 11a of the shaft 11. The contact breaker assemblyincludes an angle plate 17 having upstanding therefrom a hollow sleeve 18 upon which is pivotally mounted an insulating heel member 19 which has the cam follower 16 integral therewith. Secured to the heel 19 is a metal shell 21 which carries the movable contact 22 of the contact breaker assembly. The fixed contact 23 of the assembly is carried by a tag integral with the plate 17 and a conductive spring 24 is secured at one end of the shell 21 and urges the heel 19 to pivot about the sleeve 18 to engage the contact '22 with the contact 23.

There are two usual type of ignition distributor, one in which the contact breaker assembly of the distributor is mounted on a timing plate rotatably supported on the mounting plate so that the timing plate and therefore the contact breaker assembly can be moved relative to the mounting plate and the cam shaft of the distributor so as to alter the ignition timing of the distributor. In such an arrangement the timing plate is conveniently moved by a vacuum unit connected to the inlet manifold of the internal combustion engine. The second type of distributor dispenses with the timing plate intermediate the contact breaker assembly and the mounting plate, and the contact breaker assembly is secured direct to the mounting plate so as to be immovable relative to the casing of the distributor. A problem exists in standardizing components where both types of ignition distributor are to be provided by a manufacturer, owing to the fact that in the one case the contact breaker assembly is spaced from the mounting plate by a timing plate, whereas in the second example the contact breaker assembly is actually mounted on the mounting plate. In accordance with said one example of the present invention, in order to permit the maximum number of components common to both types of distributor, to be used, there is provided a spacer member 25. The spacer member 25 is in the form of an arcuate, steel plate which is secured to the mounting plate 12 by means of rivets. The surface of the member 25 remote from the mounting plate 12 is provided with an upstanding post 28, and the contact breaker assembly is engaged with the surface of the spacer member 25 remote from the plate 12 with the upstanding post 28 extending within the hollow sleeve 18 of the contact breaker assembly, through an aperture in the angle plate 17. clamping screw 26 extends though an arcuate slot in the angle plate 17 into a screw threaded bore 29 in the spacer 25 to permit the angle plate to be locked in position relative to the spacer 25 after being pivoted about the axis of the sleeve 18 to adjust the maximum operating gap which can occur between the contacts 23, 22 in use. The casing 10, the cam shaft 11, the mounting plate 12, and the contact breaker assembly 15 can be used without alteration for a distributor arrangement where the contact breaker assembly is mounted on a timing plate rotatably supported by way of a cylindrical bush on the spigot 14 of the mounting plate. Thus the'thickness of the spacer member 25 is so chosen that the cam follower 16 of the contact breaker assembly engages that region of the portion 11a of the shaft 11 which it. would have engaged had the arrange ment been a moving contact breaker type arrangement where the contact breaker assembly is mounted on a timing plate. It would be appreciated that in the absence of the spacer member 25 the angle plate 17 of the contact breaker assembly would have been secured di: rect to the mounting plate 12, and in this situation it would have been necessary either to use a cam shaft with the portion lla thereof differently positioned, or alternatively a different mounting plate or casing 7 whereby the cam follower 16 could engage the portion 11a of the cam shaft.

It is preferred to form the spacer member 25 in metal, so that it constitutes part of the earth side of the electrical circuit of the contact breaker assembly. However, it will be appreciated that if desired the spacer member could be formed from a synthetic resin mate- 'rial. in which case the fixed contact 23 of the contact breaker assembly would be electrically connected to the casing by way of an earth lead. As is shown in FIGS. 3 to 5, in order to save material the spacer 25 need not be formed a solid block of thickness equal to the spacing required, but can be formed as a diecast plate having integral rivets 25a projecting from one face cluding a cam portion, a contact breaker assembly mounting plate fixedly secured within said casing and spaced from the level of said cam portion of said shaft,

- a spacer member secured to said mounting plate so as thereof. The rivets each include enlarged regions adjato be held against movement relative to said mounting plate in use, a contact breaker assembly mounted on said spacer, the dimensions of said spacer being such that a cam follower of said contact breaker assembly is engageable with. said cam portion of said shaft, and, said mounting plate including means whereby said mounting plate is capable of rotatably supporting a tim ing'plate in turn supporting a contact breaker assembly.

2. An ignition distributor as claimed in claim 1 wherein the spacer member is formed from electrically conductive material, and constitutes part of the electrical circuit of the contact breaker assembly. 

1. An ignition distributor including a hollow casing, a shaft mounted for rotation in the casing, the shaft including a cam portion, a contact breaker assembly mounting plate fixedly secured within said casing and spaced from the level of said cam portion of said shaft, a spacer member secured to said mounting plate so as to be held against movement relative to said mounting plate in use, a contact breaker assembly mounted on said spacer, the dimensions of said spacer being such that a cam follower of said contact breaker assembly is engageable with said cam portion of said shaft, and, said mounting plate including means whereby said mounting plate is capable of rotatably supporting a timing plate in turn supporting a contact breaker assembly.
 2. An ignition distributor as claimed in claim 1 wherein the spacer member is formed from electrically conductive material, and constitutes part of the electrical circuit of the contact breaker assembly. 